ISS Risk Mitigation

Enhanced Dynamic Load Sensors (EDLS) on Mir

EDLS Sensors Experiment Support Module


The Enhanced Dynamic Load Sensor (EDLS) experiment is designed to measure the crew-induced forces and torques imparted on the Mir habitat module's interior surfaces. The EDLS hardware measure the magnitude and frequency of the crew-induced disturbances of the Mir microgravity environment.

Shuttle-Mir Missions
Mir-21 - Mir-23, NASA-2, NASA-4

EDLS hardware (experiment support module and torque/force sensors) was transported to Mir and installed in the Mir Priroda module in 1996. The sensors consisted of a handhold, a touchpad, and two foot restraints. The EDLS experiment involved two types of operations: passive and active. Passive session refers to the use of the sensors during nominal on-orbit activities (such as push-offs, landings, and support). Active sessions refers to the use of the sensors to record forces associated with throwing a small ball at a target.

Approximately 20 EDLS sessions (18 passive and 2 active) were performed during the Mir-21/NASA-2 missions between May and August of 1996. Failure of the experiment support module (ESM) during NASA-2 prevented experiment operations during the Mir-22/NASA-3 missions. The original ESM replaced with similar ESM for MiDSE experiment in 1997, allowing experiment operations to resume during the Mir-23/NASA-4 missions. Approximately 15 high quality EDLS sessions, 10 passive and 5 active, were performed during Mir-22/Mir-23/NASA-4 missions from February through May of 1997.

Analysis of data collected indicated that the crew loads induced on module internal structures were no greater than 70 Newtons at a frequency of range from 0 to 10 Hertz (Hz). An order of magnitude reduction in loads (from crew motions such as push-off, orientation, and landing) as compared to initial data collections was shown. The reduction is due to the zero-G experience gained by the crewmembers who, as their time in the zero-G environment accumulates, learn to minimize the their efforts to perform the intended motions thus reducing the loads imparted to the spacecraft structure and EDLS.

The Phase 2/3 benefits from this experiment is that restrictions in crew motions that were originally envisioned can be reduced for crewmembers possessing sufficient time on orbit to achieve the above-mentioned learning experience.

Lofton R, Conley C. International Space Station Phase 1 Risk Mitigation and Technology Demonstration Experiments. 48Th International Astronautical Congress; 1997 Oct 6-10; Turin, Italy; International Astronautical Federation.

Newman DJ, Tryfonidis M., van Schoor M. "Astronaut-Induced Disturbances in Microgravity," AIAA J. Spacecraft and Rockets, March-April, 1997.

Newman DJ, van Schoor M. "Dynamic Load Sensor Experiment: Background, Science Requirements, and Preliminary Design," white paper, November 18, 1992.

Newman, DJ, "Dynamic Load Sensors (DLS) Spaceflight Experiment," report and world wide website,, MIT, Dept. of Aeronautics and Astronautics, MVL Report 96-1, January, 1996.

Dynacs Engineering Company. ISS Phase 1 Risk Mitigation Experiments and Technology Demonstration summaries and Lessons Learned. ISS Phase 1 RME Forum. JSC 28080 Revision A. Houston, TX. August 1998.

Principal Investigators
Sherwin Beck
NASA/Langley Research Center

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